Virtual 2720 1024

and restart X.

The Intel page you linked to says larger than 2048×2048 doesn’t work with the current drivers. I don’t know if 2720×1024 is larger or not, if it is, you can try 1440×1924 and have the second screen above/below the first.

I “sorta” got it working, but on an 855GM chip (older card) and some xorg.conf configurations need to be added. The relevant bits on my xorg.conf follow:

Section “Device”
Identifier “Intel Corporation 82852/855GM Integrated Graphics Device”
Driver “intel”
BusID “PCI:0:2:0″
Option “monitor-LVDS” “Generic Monitor”
Option “monitor-VGA” “VGA1″
Option “monitor-TMDS-1″ “TV1″
EndSection

Section “Monitor”
Identifier “Generic Monitor”
Option “DPMS”
HorizSync 28-64
VertRefresh 43-60
Option “PreferredMode” “1280×768″
Option “Position” “0 0″
EndSection

Section “Monitor”
Identifier “VGA1″
Option “RightOf” “Generic Monitor”
#Option “Enable” “true”
#Option “Rotate” “left”
Option “PreferredMode” “1024×768″
Option “Position” “1280 0″
EndSection

Section “Screen”
Identifier “Default Screen”
Device “Intel Corporation 82852/855GM Integrated Graphics Device”
Monitor “Generic Monitor”
DefaultDepth 24
SubSection “Display”
Depth 15
Modes “1280×768″
EndSubSection
SubSection “Display”
Depth 16
Modes “1280×768″
EndSubSection
SubSection “Display”
Depth 24
Modes “1280×768″
Virtual 2560 1280
EndSubSection
EndSection

Then I ran
xrandr –output VGA –right-of LVDS –auto

and it worked.

Not perfect but if you really want it, try this. One more thing: if when GDM starts the VGA monitor is plugged in X11 assumes that is the main display and breaks everything so my advice is to not start GDM with the external monitor plugged in.

just guessing here, not a linux user for quite some time. Do you have enough video ram to run both monitors at full depth?

I would try (just to see if this is the case) reducing to screen size to 800X600.

Best regards,